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D Davison

Publications and source records attributed to D Davison.

8 recordsLinked to original sources
PubMed1991

Mammalian hexokinase 1: evolutionary conservation and structure to function analysis.

We have amplified and sequenced the complete coding region of bovine hexokinase isoenzyme 1 (HK1) from brain RNA with PCR primers selected for sequence conservation. The sequence information was analyzed to evaluate the evolutionary and structure-function relationships among the mammalian and yeast HK isoenzymes. Structure to function analysis identified an unduplicated, invariant N-terminal domain involved in HK1 outer mitochondrial membrane targeting, as well as putative carbohydrate and nucleotide-binding sites in the regulatory and catalytic halves of HK1 essential to enzyme function. The ATP-binding site in the catalytic half of the HK1 protein resembles nucleotide-binding regions from protein kinases, with the single amino acid replacement (lysine to glutamate) in the ATP-binding site of the amino half explaining the loss of HK1 catalytic function in the regulatory domain. Sequence comparisons suggest that the 50-kDa mammalian and yeast glucokinases arose separately in evolution. In addition to providing valuable phylogenetic and structure-function insights, this work provides an efficient strategy for rapid cloning and sequencing of the coding regions for other HKs and related proteins.

Amino Acid Sequence↗
PubMed1987

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Burnout, Professional↗
PubMed1985

Genetic and physical studies of a portion of the white locus participating in transcriptional regulation and in synapsis-dependent interactions in Drosophila adult tissues.

We have identified and sequenced the portion of the white locus affected by an idiosyncratic set of white mutant alleles (the wsp alleles). The affected white locus portion (wsp region) extends from ca. 590 base pairs (bp) to ca. 1270 bp 5' to the apparent start site for the major white transcription unit. Based on the properties of these mutant alleles, we infer the existence of two distinct cis-acting regulatory elements in the wsp region and a third element mapping 3' to this region (3' to position ca. -670). Our analysis allows us to define the apparent position of one of the two wsp region elements with substantial precision. Examination of the DNA sequences in this region suggests that it is functionally similar to the enhancers identified in vertebrates. This same element participates in synapsis-dependent genetic interactions, suggesting a largely unexpected relationship between enhancer-like, cis-acting genetic elements and the genetic elements responsible for the synapsis-dependent genetic interactions in trans revealed by the existence of transvection effects. Our results further suggest that a presumptive regulatory locus (suppressor-of-white-spotted) regulates white transcription in adult tissues and is not involved in regulating white expression in larvae. We discuss the regulation of white expression in light of our studies. We also demonstrate unusual structures for an X-ray-induced deletion and a spontaneous deletion.

Alleles↗
PubMed1985

A detailed developmental and structural study of the transcriptional effects of insertion of the Copia transposon into the white locus of Drosophila melanogaster.

The copia insertion responsible for the wa mutation is 3' to the white promotor and in the same transcriptional orientation as white. First, we have analyzed the effects of the wa copia insertion on levels of polyadenylated white transcripts and find large, developmentally programmed effects. Second, we have isolated and sequenced an LTR-excision event involving the copia insertion at wa. This represents the first documented case of an LTR-excision event in Drosophila. This single copia LTR has developmentally programmed effects on white transcript levels qualitatively similar to the intact copia element. Third, we have characterized the structures of white transcripts from wa. We find polyadenylated white transcripts apparently having 3' termini in or near the 3' LTR of the wa copia insertion, as has been reported in limited studies of wa transcription in adults by others. These earlier studies also revealed wa transcripts apparently corresponding to polyadenylated terminus formation in the 5' LTR of the copia transposon; however, our more detailed studies reveal that these transcripts probably have other origins and that little, if any, polyadenylated terminus formation for white transcripts occurs in the 5' LTR of the wa copia insertion. Moreover, we find no polyadenylated terminus formation for white transcripts occurring in the single LTR of the wa LTR-excision product. Fourth, we find that each of three mutant alleles at su(wa) produces elevated levels of several classes of RNAs apparently corresponding to transcriptional readthrough of the wa copia transposon. Elevated levels of one presumptive readthrough transcript were observed previously in one su(wa) mutant strain. Fifth, we have confirmed the existence of a transcript initiated in the 3' LTR of the wa copia insertion and find the levels of this transcript to be strongly influenced by developmental stage and genetic background. Lastly, we have analyzed white transcripts produced by the whd81b11 allele, which carries an insertion of copia in the opposite transcriptional orientation and in a different position than the wa copia insertion. In contrast to the wa copia insertion allele, the whd81b11 allele produces polyadenylated white transcript levels very similar to the w+ case at the stages examined. Moreover, the whd81b11 copia element apparently produced polyadenylated terminus formation in white transcripts and we observe no effect of the allelic state of su(wa) on apparent readthrough of this stop site.(ABSTRACT TRUNCATED AT 400 WORDS)

Alleles↗
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Base Sequence↗